For its 100 year celebration, Grand Central has a nice display with some of the history the terminal has seen since the beginning in Vanderbilt Hall. The exhibit is up through tomorrow, though so check it out for yourself or take a look at what I found on my visit! And if you need a bite, there's plenty to eat from the famous Oyster Bar to the food hall on the lowest level and the beautiful gourmet market. at street level. If you go tomorrow during the day there's even a free tour at 12:30pm, given by Justin Ferate and Peter Laskowich:
"Meet INSIDE the atrium of 120 Park Avenue on the southwest corner of Park Avenue and East 42nd Street – across the street from Grand Central Terminal. There are benches, chairs, and tables inside for those who arrive early. Here is a link with more information: <http://www.grandcentralpartnership.org/things-to-do/tours> "